Rim-fire ammunition



July 3,j 1923. 1,461,013

H. D. HODGE RIM FIRE AMMUNITI ON Filed July 15 1920 Patented July 3, 1923.

*y UNITED STATES PATENT GFFICE.

HOWARD D. HODGE, v01?', NEW YORK, N. Y., ASSIGNOR T0 GEORGE RAMSEY, OF NEW YORK, N. Y.

RIM-FIRE AMMUNITION.

i Application filed July 13, 1920. Serial No. 395,898.

To all whom it may concern.'

Be it known that I, HOWARD D. Hoven, a citizen of the United States, and a resident of the city of New York, in the county of 5 New York, State of New York, have inventedv certain new and useful Improvements in Rim-Fire Ammunition, of which the following is a specification.

This invention relates broadly to ammunition and more specifically to rim lire cai'- trdges.

' The principal object of the present inven- `tion is to provide reinforcements for a rim re or similar cartridge to permit use of such cartridges with high pressure powder in existing weapons of standard types.

Another object of the present invention is to provide reinforcements for n standard rim re cartridge, without changing the compressibility of the rim carrying the priming whereby the cartridge may be used with powder having high ballistic efiiciency,

, and, which use is impossible under present conditions and methods of construction..

A further object of the present invention is to provide reinforcement for a rim fire cartridge to obviate bursting of the rim under high powder pressures, and whereinthe y reinforcement does not affect the sensitiveness of the rim to the striker or firing pin of the ordinary firearm. t

A still further object of the present 1nvention is to provide a rim fire cartridge with a pressure sustaining member adapted to prevent excessive pressure from reaching the duc-tile portion of the rim carrying the priming.

A still further andL more specific obJect of the present invention is to provide a pressure sustaining cup adapted to be seated in the head of a rim re cartridge to prevent excessive powder pressure reaching the priming rim, and also to efficiently direct the'flame from the priming composition into the powder charge.

Other and further objects of the present invention will in part be obvious and will in part be pointed out hereinafter in the specification by reference to the accompanying drawings forming a part of the specification and wherein like parts are represented by like characters throughoutthe several figures thereof.

Figure l is a section through a rim iirc shell illustrating one form of reinforcement in accordance with my invention.

Figure 2 is an end View of the reinforcing cup illustrated in Figure l and showing the Hash-conveying grooves.

Figure 3 is a perspective View of the same type of reinforcing cup.

Figure 4 illustrates a blank from which the reinforcing cups may be formed.

Figure 5 is a view showing a modification having a series-of openings through which the priming is adapted to fire directly into the powder chamber.

Figure 6 illustrates the preferred method of securing the cup in position in a shell.

Figure 7 illustrates a cup of the type shown in Figure 5 secured by the method illustrated in Figure 6.

The rim fire type of shell is particularly adapted for cartridges of small diameter or caliber for the reason that the heads of such shells are so small as to render the adoption and use of separate center fire primers inexpedient and expensive. In small calibers the powder space is small and it is thereforedesirable that powder of high ballistic etticiency be used in'this type of ammunition where any considerable range is desired. Experience has shown that where powder pressures in rim fire cartridges have been increased beyond that attained by black powder the rims burst under such powder pressure long prior to the attaining of pres sures that would be most effective and eiiicient. Copper is commonly utilized as the most satisfactory material for rim fire cartridges for two reasons-:first:l the easily controlled ductility of the copper enables the maker to select his method so that the firing pin or striker will crush the primer rim without severing the crushed portion from the surrounding metal. Second: because other metals have been found to cause deterioration in the most commonly used and most satisfactory priming' compositions, namely, those using fulminate of mercury as one of the constituent ingredients. Attempts to reinforce rim fire cartridges have heretofore. been made by thickening the metal. This led to misfires due to the tendency of the thicker metal to flow the fulminate priming inwardly without detonating the same when the rim was struck by the tiring pin, and also due to the fact that theI lirearxns in use are equippedwith liring mechanism `capable of crushing, without cuttingvor breaking, the sensitive soft rim in common use, but. not capable of crushing the. hea-vier rim. The same troubles have been encountered. by use of stronger metalssuch as brass-and as previously set forth:L and furthermore brass is one of the metals which causes rapid deterioration of fulminate of mercury.

The present invention overcomes the foregoing di'tliculties by leaving the sensitiveness of the priming Vrim entirely undisturbed and by providing means to prevent the excessive powder pressure from reaching the weaksensitive rim. This invention is preferably carried out by providing the base of the standard rim fire shell with an interior pressure cup constructed to permit the priming to fire the powder charge and to receive Aand support the gas pressures developed' by the burning powder and prevent such pressures from reaching the rim. In practice the pressure receiving members may be formed of suitable cups` preferably copper, which are inserted in the shells, after the rimis` filled with priming composition and which are maintained in position by slightly distorting the reinforcing cup to expand a very slight port-ion thereof1 under the shoulder of the primer rim. This construction obviates any possibility of the reinforcing cup leaving the shell when the shell is fired. The reinforcing cup andthe shell are preferably -formed by drawing the cup from a sheet of .metal so as to provide spring segments on the side of the cup, which spring segments exert an outward pressure against the inside wall of the shell when the cup is in position. It has been found in practice with central fire cartridges that .the opening leading from the primer to the powder chamber may be so proportioned, and in practice is, as to be large enough to permit thelame from the primer to penetrate and suitably ignite the powder charge at the same time to be sm all enough to prevent the combustion gas pressure from bursting the primer cup. I desire to utilize this principle in connection with my -invention so that-the openings leading from the primeiwwill be su'liciently large to insure efficient operation of the priming at the same time be sufficiently small to prevent the passage of sufficient gas pressure to unduly increase back pressure in the priming rim during the normal firing of the cartridge.

Referring now to the drawings the standard rim fire shell 1 is provided with the usual composition priming Q which is secured by adhesion with the walls of the firingwrim 4. The reinforcing cupe lits the interior of the standard rim lire shell l and is seated against the head of this shell in such 'manner that the priming composition is confined between the'walls of the rim #l and the side wall of the reinforcing cup 5' so that when the striker or iii-ing pin compresses the rim there 'is no possibility of the priming composition breaking away from the rim and thereby causing a mislire, As shown in Figures l, 2 and 3, the reinforcing cup comprises a substantially cylindrical walled cup having the head thereof provided with a liring opening 6 from which leads a plurality of radial liring grooves 7 so that `when the priming is exploded the flame and incandescent gases travel through the grooves and tiring opening into the powder chamber S within thel reinforcing cup 5. By this construction the flame of the priming is directed to the center of one end of the powder chamber .along the longitudinal axis thereof so that all the advantages of a center fire cartridge are secured by this rim lire shell. The reinforcing' cup may be formed from a blank 9, such as is illustrated in Figure el, in such manner as to provide the cup `with a plurality of spring segments l0 which tend to tightly' grip the interior wall'of the shell l. The preferred method of securing the retaining cup within the shell is illustrated in Figures G and T and comprises an enlargement, as at 12, formed on the retaining cup and adapted vto engage the shoulder 14 adjacent the firing rim This enlargement may be conveniently formed by providing compressible member l5, such'as a paid ot suitable rubber mounted upon the end of a suitable plunger 1G, preferably metal, which may be used in seating the reinforcing cups* in the shells. 7 hen such a device is inserted in the cup, with the shells seated on a Hrm anvil, pressure on the plunger 16 will cause the compressible member 16 to expand laterally thereby slightly stretching the reinforcing cup suliiciently to expand the same under the shoulder 14 as lspecified the shell heilig retained in a suitable holder, not shown,.during this operation. lVhe're such interlocking constructions are provided between the reinforcing cup and the shell it may be desirable to form reinforcing cups with continuous side walls, as shown in- Figure 5. and thereby omitting the spring segments. As a modification of the liring openings a series of small holes 17 may be provided infthe reinforcing cup and leading fromthe priming directly to the powder chamber 8.v4 ln allcasesit is desirable that the tiring openings be so proportioned in size as to enablethe priming to effectively ignite the powder charge but.4 at the saine time be sufficiently small to prevent excessive back pressure acting upon the firing rim, as has been previously specified. It is'to be noted that the high pressure in the 'powder chamber to reach the rim must be transmitted through the small openings and through the annular chamber which was filled by the priming composition. Before sufficient gas has passed into the priming chamber to increase the pressure therein up to the bursting point of the rim the projectile has left the muzzle of the gun and the gas in the cup is released to atmosphere.

Realizing that my invention may be embodied in structures other than the specific construction herein disclosed, it, is my desire i that the said disclosed construction be considered merely as illustrative and not in the limiting sense.

Having thus described my invention whatl I claim is:

l. In a rim fire cartridge, a shell adapted to form asuitable powder chamber, a priming retaining` rim of relatively soft thin material, a priming composition within said rim, and a re-inforcing cup mounted within the head of said shell and having a portion extending within said rim sufficiently to interlock said cup with said shell, saidcup being provided with flame openings to permit the priming material to fire the powder charge within the shell when the priming is ignited, and said openings being sufficiently small to retard the backward flow of gas pressure from the burning powder, thereby preventing excessive powder pressures from reaching the rim of the shell.

2. In a rim fire cartridge, a shell adapted ,to form a suitable powder chamber, a primsufficiently to interlock said cup with said shell, said cup being provided with flame openings to permit the priming material to fire the powder charge within the shell when the priming is ignited; and said openings being sufficiently small to retard the backward flow of gas pressure from the burning powder, thereby preventing excessive powder pressures from reaching the rim of' the shell.

3. In a rim fire cartridge, a shell adapted to form a suitable powder chamber, a priming retaining rim of relatively soft thin material, a priming composition within said rim, and a re-inforcing cup mounted within the head of said shell and having a convex beaded portion extending within said rim sufficiently to interlock said cup with said shell` said cup being provided with flame openings to permit the priming material to fire the powder charge within the shell when the priming is ignited, said convex beaded portion being constructed to be forced tightly into said priming retaining rim by the force of the powder gases.

4. In a rim re cartridge, a shell adapted to form a suitable powder chamber, a priming retaining rim of relatively soft thin material, a priming composition within said rim, and a re-inforcing cup mounted within the head of said shell and having a portion extending within said rim sufficiently to interlock said cup with said shell and allow sufHcient space for the priming, said cup being provided with small flame openings to permit the priming material to fire the powder charge within the shell when the priming is ignited.

5. In a rim fire cartridge, a shell adapted to form a suitable powder chamber, a priming retaining rim of relatively soft thin material, a priming composition within said rim, and a re-inforcing cup mounted within the head of said shell and having a convex beaded portion formed to comprise a small rim extending within said priming retaining rim sufficiently to interlock said cup with said shell, said cup being provided with flame openings to permit the priming material to fire the powder charge within the shell when the priming is ignited, said convex beaded portion being constructed to be forced tightly into said priming retaining rim by the force of the powder gases.

6. In a rim fire cartridge, a shell adapted to form a suitable powder chamber, a priming retaining' rim of relatively soft thin material, a priming composition within said rim, and a re-inforcing cup mounted within the head of said shell and having a portion formed to comprise a small rim extending within said priming retaining rim suf'- ficiently to interlock said cup with said shell and allow sufficient space for the priming, said cup being provided with small flame openings to permit the priming material to fire the powder charge within the shell when the priming is ignited..

7. In a rim fire cartridge` a shell adapted to form a suitable powder' chamber, a priming retaining rim of relatively soft thin material, a priming composition within said rim, and a re-inforcing cup mounted within the head of said shell and having a convex beaded portion formed to comprise a small rim extending within said priming retaining rim sufficiently to interlock said cup with said shell and allow sufficient space for the priming, said cup being provided with small flame openings to permit the priming material to fire the powder charge within the shell when the priming is ignited. said convex beaded portion being constructed to be forced tightly into said priming retaining rim by the force of the powder gases.

HOWARD D. HODGE. 

